Labour will accuse David Cameron of selling off the NHS without permission and demand a halt to privatisation until after the general election.

In a speech later, shadow health secretary Andy Burnham insists that forced privatisation is being pushed through "at pace and scale".

He will warn that contracts are being signed now which will bind the next government.

Mr Burnham will also claim the Prime Minister was "not up front" about his intentions for reform during the 2010 campaign, leaving voters with no say.

Andy Burnham says contracts are being signed without a public mandate

In a speech in Manchester, the shadow health secretary will say: "Labour publishes new analysis today which shows that NHS forced privatisation is entering new territory and becoming harder to reverse.

"Contracts are being signed that will run for the five years of the next Parliament, and beyond. This is not acceptable.

"Contracts like this will tie the hands of the next Government in a crucial area of public policy.

"But, even worse, they are being signed without a mandate from the public. The Prime Minister was not up front about these plans at the last election.

"He needs to be reminded that he has never been given the permission of the public to put the NHS up for sale in this way."

David Cameron has been accused of forcing through privatisation

Since the Health and Social Care Act was introduced, the bidding for two contracts for cancer care in Staffordshire has been opened up to the private sector.

The contracts are worth a total of £1.2bn and last for 10 years.

Bids have also been invited for a five-year contract worth £800m for the care of older people in Cambridge.

Mr Burnham will say that voters face the choice of a public, integrated NHS under Labour or fragmented and privatised service under the Conservatives.

He has written to NHS England boss Simon Stevens calling for a halt to any further contracts for NHS clinical services being signed until after the next election.

"When his reorganisation hit trouble and was paused, David Cameron explicitly promised that it would not lead to more forced privatisation of services.

"But, as always with the NHS and this Prime Minister, the rhetoric and the reality don't match. On his watch, NHS privatisation is being forced through at pace and scale."

A Conservative Party spokesman accused Labour of posturing.

"The NHS is an asset to be valued and protected - it deserves better than this speech," the spokesman said.

"The real choice at the next election will be between a Conservative Party which is delivering a more efficient and effective NHS - and a Labour Party which has learned nothing from its past mistakes."